Camphor-derived alcohols: An anomalous reaction of 3-hydroxycamphor and the influence of internal alkoxides on the alkylation stereochemistry of glycinate imines
✍ Scribed by John M. McIntosh; Kenneth C. Cassidy; Luca C. Matassa
- Book ID
- 104204793
- Publisher
- Elsevier Science
- Year
- 1989
- Tongue
- French
- Weight
- 648 KB
- Volume
- 45
- Category
- Article
- ISSN
- 0040-4020
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✦ Synopsis
emped Imine formodon between 3-hy.lmqcomphor and tetf. butyig3rinote led to & the substitudon pvducl al the 3-posidon. zinc-acetic acid tmotmenf of a offorded 3-acekuyomphor. Alkylodon of the imi~:e /mm from nmonphor and ten. buel @inare gave no stereosekcdon. Al@hztion of the iminefmm from IO-hydiqmethykampku and reti. buyi glycinote gave stetzoselechiries infetiw to thase obtained fronl the imine of camphor iurl/ (J), art oldol condeusodon whh benzaldeh_yde, a traction not possible with & was effected in 71%@ld. For the past live years, we have been engaged in the examination of various aspects of alkylation reactions of the iminc (1) derived from camphor and rcn.-butyl glycinatc. Our results which have been fully documented3 indicate a surprising dependency of the alLytation stereochemistry on the electronic nature of the clcctrophilic species which does not seem to exist in the alkylations of other glycine imines4 One further unexpected result of thii work has been our inability IO effect aldol condensations on the anion of 1. Such a reaction would protide a routu IO amino alcohols which holds some promise of allowing stcrcochemical control. both in the relative (threo VS. erythro) and absolute (R \T. S) sense. WC had cxpcndcd considcrahlz effort on this reaction using hcnzaldchydc as a ICSI case with uniformly unencouraging results. 3c Thc.sc failures in thr cast of 1 parallrl the results ohtaincd by Stork' on other iminos of glycinale esters. Stork attributed these failures to the soft nature of the anions. Recently reactions of 1 and other imincs of glycine. including aldol condensations with henzaldehydcs having an electron withdrawing group (e.g. pNO*). have been rcportcd IO proceed under ph;Lsc transfer conditionsP Also. results have been reported by several groups which suggested that enolntcs of imincs possessing other chelating sites might hehavc signilicantly differently from enolates of imincs like 1. Aldol condensations and alkylations of imincs of ketopinic acid' and hydroxypinanone4 have been reported and it seemed that the presence of an hydrov group in the Jerivatizine aecn[ might affect the alkylation reaction and thus afford more _ _ information on the stcreochemiwl pathway. The rcrctivc intcrmcdiatc would necessarily bc a dianion. which might change the rcactivity of the imine anion significantly. In addition. the three methyl groups on camphor have always been assumed to hc the important stereochemical feature which causes the asymmetric induction. However. to our laowlcdgc. no direct cvidencc on this point has been